Thermoplastic polymers having a high degree of heat resistance or thermal stability are the object of intensive research and development in many laboratories throughout the world. Because thermoplastic materials comprising these polymers can be molded rapidly and efficiently to articles of simple or of complex design, mass production techniques can be utilized to provide a wide variety of useful products. Heat resistant thermoplastic polymers thus offer important advantages that can be utilized in applications such as electrical components, wire coatings, automotive parts, aircraft parts and the like. Often such polymers can be used in the form of composite materials which contain high temperature resistant fibers and fillers.
Arylene sulfide/sulfone polymers are thermoplastic polymers known in the art, and processes for making these polymers are disclosed in various U.S. Patents of R. W. Campbell, e.g. U.S. Pat. Nos. 4,016,145, 4,102,875, 4,127,713 and 4,301,274. Although these patents represent significant and valuable advances in the art, there is a need for a simplified process which can provide aromatic sulfide/sulfone polymers having high molecular weight.
In particular, problems have been encountered in obtaining a sufficiently high molecular weight aromatic sulfide/sulfone polymer whenever the concentration with respect to the sulfur-containing compound utilized in the preparation thereof has been varied over a wide range. Such a variation in concentration may be required for example, in scaling up suitable polymerization processes from a smaller size polymerization vessel to a larger vessel. Since larger vessels often will utilize different stirring means, the efficiency of stirring may vary significantly from one vessel size to another which in turn may require the utilization of a more dilute polymerization reaction mixture for those situations which encounter a less efficient stirring means. For reasons not completely understood, variations with respect to the concentration of a sulfur-containing polymerization component can cause difficulty in achieving the desired high molecular weight aromatic sulfide/sulfone polymer.
Accordingly, an object of our invention is to produce aromatic sulfide/sulfone polymers exhibiting high molecular weight.
It is a further object of our invention to provide a simplified, readily controllable process for producing high molecular weight aromatic sulfide/sulfone polymers.
A further object of our invention is to provide a simplified, readily controllable process for producing high molecular weight aromatic sulfide/sulfone polymers over a wide range of concentration with respect to the sulfur-containing component of the polymerization reaction mixture.
Other objects and aspects, as well as the several advantages of our invention are apparent from a study of this disclosure and the appended claims.